Electrical safety device.



E. ROBERTS. ELECTRICAL SAFETY DEVICE. APPLICATION FILED JuLYzl. 1917.

www; Y Edward @SHQ E. ROBERTS. ELECTRICAL SAFETY DEVICE.

APPLICATION FILED .IULY2I. |917. L,2?6962 Patented Aug. 27, 1918.

2 SHEETS-SHEET 2.

E STATE@ @AEN @FCE EDWARD ROBERTS, OF DETROIT, MICHIGQAN.

ELECTRICAL SAFETY DEVICE.

Speoicaton of Letters Patent.

Patented Aug. 27. 1913.

Application led July 21,' 1917. Serial No. 181,956,

trical Safety Devices, of which the following is a specification,reference being had therein to the accompanying drawings.

1n the operation of large presses, punches, and various other types ofmachines, many workmen have been seriously injured by attempting toadjust material and perform necessary and unnecessary duties after amachine has been placed in operation. Furthermore, some machines, aslarge presses or dies require the attention of two or more attendants,one or more at each side of the machine, andy it is not always possibleor convenient for the attendant -having charge of starting the machineto signal to the other attendants that the machine is about to be placedin operation. As a matter of fact, the majority of accidents happeninconnection with machines attended by two or more workmen. v

The primary object of my invention is to y provide a novel electricalsafety device which will necessitate the hands of workmen being inpredetermined positlons from the beginning to the end of machine oerations, thus precluding any danger o the workmen placing theirV handsin dangerous positions during the operation of the machine.

Anotherobject of my invention is to provide an electrical safety devicethat may be easily and quickly installed and associated with thestarting and stopping mechanism of a machine, the device being of such anature that the machine cannot be placed in operation by one hand butnecessitates both hands of an operator or the hands of all".

operators. Y v

A still further object of my .invention is to provideA a simple, andinexpensive safety device that is applicable to various types ofmachines and highly eiiicient for preventing carelessness on the part ofmachine operators.

My invention will be hereinafter specifically described and thenclaimed, and reference will now be had to the drawings, whereini Figure1 is a side elevation of the safety device as applied to a suitablemachine,

showing the device designed for a single operation;

Fig. 2 is any enlarged longitudinal sectional view of a magnetic switchforming part of the device;

Fig. 3 is a diagrammatic View of the electrical connections for a oneman device;

Fig. 4 is a similar View of the electrical connections for a two mandevice, and

Fi 5 is a similar view of the device as wire for a plurality of workmen.

As illustrating a conventional form of machine, there is shown in Fig. 1a housing 1 for a stationary member 2 and'a reciprocable member 3, thelatter ybeing carried by a head 4 reciprocated on guides 5 by extensions6 operated by drive shafts 7. On the drive shaft 7 is a loose gear wheel8 having a clutch member 9 and said loose gear wheel meshes with a gearwheel 10'on a shaft 11 driven from a suitable source of power, as anelectric motor. At the end of the machine, there is a bracket or bearingl2 assisting in supporting the drive and driven shafts 7 and 11respectively, and on the drive shaft 7 is slidably keyed a clutch member13 adapted for establishing rotative continuity Ibetween the ear wheel 8and the shaft 7 by intermes ing with the clutch member 9. Theclutchmember 13 is, constantly pressed by a spring 14 between-said clutchmember and the bracket 12, and said clutch member has a peripheralgroove 15 provided with a. cam portion 16. Extending into the groove 15is the arm 17 of a fulcrum lever 18, carried by the bracket 12,saidlever having the short end or portion thereof provided with a weight19 so that the arm 17 of said lever will be normally retained in thegroove 15 of the clutch member 13. When the arm 17 is removed from thegroove of the clutch member 13, the ex pansive force of the spring 14will force the clutch member into mesh with the clutch member 9 and thusplace the machine in operation. When the lever 18 is released the arm 17will engage in the groove 15 and on the cam'portion 16 of said groovereaching the arm 17, the clutch member 13 is automatically retractedagainst the tension of the spring 14 and there is a cessation in theoperation of the machine. lt is the present practice to operate thelever 18 by a treadle or lever, and to install my safety device, Idispense with such operatlng means.

The safety device includes a conventional form of solenoids 2O mountedon the bracket l2 withV the core 2l thereof connected to the long arm orportion or the lever i8 by a link 22.

ln front of the reciprocable head 4 and at a height convenient to thehands of an operator, is a support 23 suitably attached to the housing.@n the support 23 in spaced relation, are push buttons orinstrumentalities 24 necessitating a constant pressure for handmanipulation to maintain electric circuits, and connected to these pushbuttons are lead-in wires 25.

Suit-ably connected to the housing 1, preferably near the top thereof,is a casing 26 and in said casing are contact members 27 and 28. llhesecontact members are in proximity to a slot 29 in an end wall ot thecasing 26, and extending through the slot 29 is a switch arm 30, whichis pivoted, as at 3l, within the casing. The outer end of the switch arm30 is connected by a link 32 and a spring 33 to one of the eccentrics 6or the reciprocable head 4, so that the switch arm 30 will be lowered insynchronism with the reciprocable head 4. lo elevate the switch arm 30 asmall retractile spring 34 connects said switch arm to the casing 26.

ln the casing 26 is an electromagnet 35 having pole pieces 36'adapted tobe engaged by an armature 37 carried by the switch arm 30 and saidelectromagnet is connected by a wire 38 to the contact memloer 28.

Another wire 39 from the electromagnet extends out of the casing 36 andis connected t0 the solenoid 20, said wire having a branch 40 extendingto one of the push buttons 24.

The switch arm 30 is connected by a wire 41 to the other push button 24,and the contact member 27 is connected by a wire 42 to the solenoid 20.All of the wires are.

suitably insulated and insulation material is `used in connection withthe casing 26, switch arm 30 and contact members 27 and 28 to preventshort circuits.

From the electrical connections shown in Figs, l, 2 and 3, it isapparent that both of the push buttons 24 must be pressed and maintainedunder compression to energize the solenoid 20'so that the core 21thereof will be lowered and the arm l? or the lever 18 shifted torelease the clutch member i3 nar/acca and place the machine inoperation. The clutch as shown is intended to prevent a repeat operationof the machine, and various other types of clutches can be used whichwill immediately cause a cessation in the operation of the machineshould the operator remove his hands from the push buttons 24,

ln Fig. 4, there is shown a diagrammatic view of the electrical wiringof a machine that has a set of push buttons 43, at each side thereoi2and besides these push buttons there are signal lamps 44 and switches45. The switches 45 permit of either set of push buttons being renderedinoperative but with both switches closed the lamps 44 will indicate-from one workmen to another when certain circuits are completed for theoperation of a machine.

ln Fig. 5 of the drawing there are two sets of push buttons 46 for eachside of the machine and in the electrical wiring of said push buttonsthere are included switches 47 and visible signals 48.

lt is therefore apparent that the safety device can be used on vervlarge machines and controlled by a pluralitv of workmen, and while inthe drawings there are illustrated the preferred embodiments of myinvention, it is to be understood that the structural elements aresusceptible to such variations and modiiications as fall within thescope of the appended claim.

"W hat l claim is:--

ln an electrical device for machines, the combination with a source ofelectrical-energy, a clutch controlling the operation or the machine,and an arm controlling the operation of said clutch, of a solenoid in.circuit with said source of electrical energy and adapted to beenergized to have the core thereoil shift said clutch control arm, pushbuttons adapted for completing the circuit of said solenoid, and aswitch arm shifted by said machine to break the circuit o said solenoideven though the push buttons are depressed.

ln testimony whereof I aiiiX my signature in the presence of twowitnesses.

EDV/ARD ROBERTS.

"Witnesses:

ANNA M. Dorn, KARL lrl. BUTLER.

